Process of desulfurizing sulfur-bearing petroleum.



UNITED STATES Patented. November 24, 1903;.

PATENT OFFICE.

THEODORE F. COLIN, or ELIZABETH, NEW JERSEY.

srnczrxcA'rxon rowin part of Letters Patent No. 744,720, dated November 24, 1903. Application filed October 17, 1902. Serial No. 127,718. (No specimens.)

To all whom it may concern.-

Be it known that I, THEODORE F. COLIN, a citizen of the United States, residing at Elizabeth, county of Union, State of New Jersey, have discovered a new and useful Process of Desulfnrizing Sulfur-Bearing Petroleum, of which the following is a specification.

In a prior patent granted to me November 5, 1901, No. 685,907, I described a process for desulfurizing Ohio petroleum distillates, which consists in treating them with sulfuric acid and copper. In applying this process on a large scale I have found that while it works quickly and completely in the case of the saturated hydrocarbons with distillates containing unsaturated hydrocarbons produced by the decomposition incident to distillation at high temperatures it seems that by-products containing copper were formed, which are very soluble in petroleum and removable therefrom with difficulty, while at the same time the desulfurization was incomplete. When dilute acid was employed to avoid producing ether-sulfuric acids by combination with the unsaturated hydrocarbons, its action was too weak to cooperate with the copper oxid in decomposing the hydrocarbon sulfids.

I have found that a mixture of a salt of a metal having two or more states of oxidation easily interconvertible, like iron, manganese, nickel, cobalt, or chromium," with a halogen compound, like sodium chlorid, hydrogen chlorid, &c., and with a salt of a metal which gives a sulfid insoluble in an acid solution,

like copper, silver,'mer'cury, lead, bismuth, cadmium, antimony, and tin, all in aqueous solution, desulfurize petroleum distillates. Of the metals of the first category described I prefer the use of iron as being the most easily obtained and cheap. Of its commercial salts the so-called green vitriol or iron sulfate, containing a mixture of ferrous and ferric sulfates, is easiest obtained. A mixture of this with sodium chlorid Will produce, in part, ferrous and ferric chlorids.

I Of the halogen compounds the most available is evidently sodium chlorid. Of the metals of the second category I prefer to use copper, and of its salts the most available is the sulfate. On mixing its solution with sodium. chlorid a solution of cupric chlorid will be obtained. The reacting solution therefore will consist, substantially, of iron and copper chlorids and will be slightly acid, owing to the formation of basic iron salts, during which some free acid will be liberated. The

tion and chlorination of the petroleum. An

excess of iron or copper contaminates the oil with these metals. Still slight variations in conditions do not affect the result sensibly.

In order to save time and material, it is advisable first to remove from the distillate the gaseous sulfur dissolved in it, probably as hydrogen-sulfid, and this may be easily accomplished by agitating the oil with a little alkali, as'soda, letting it settle and drawing 01f the alkaline sludge. With some-oils as much asone-fourth part of the total sulfur therein maybe thus removed. The oil is now ready for treatment for the removal of the more refractory sulfur.

To describe my invention in detail, I took one hundred and twenty-five cubic centi-' meters, or about one hundred grams, of a sixty-per-cent. distillate made from Ohio petroleum,which consisted of about equal quantities of saturated and unsaturated hydrocarbons and represented about all the'distillate available for illuminating purposes. After washing it with soda, as described above, I added ten cubic centimeters of a cold saturated copper-sulfate solution, ten cubic centimeters of a similar solution of ferrous sulfate,

and ten cubic centimeters of a like solution of sodium chlorid. The whole was agitated by an air-blast at ordinary temperature (about 17 centigrade) for a quarter of an hour, until, on taking a few drops of oil and making them alkaline with a small quantity of an alcoholic solution of sodium ethylate, no red color was produced when a drop of an aqueous solution of sodium nitroprussid was added, thus showing the absence of hydrocarbon sulfids and proving that the desulfurizationwas complete. After separating the oil from the aqueous solution it was treated in the usual way with acid,water, and a little caustic soda. The resulting product was a refined distillate which stood completely the usual tests. The solutions taken were only slightly acid, nearly neutral, but after the treatment appeared to be slightly basic, containing a little of a basic iron salt. This was evidently owing to the loss of some hydrochloric acid which was blown away in the air-current. No copper sulfid was noticed in the precipitate. It seemed probable that it was at once oxidized to sulfate under the influence of the air-currentand the oxidizing mixture. This feature allows of the mixture being used repeatedly,since some of the ingredients are brought back to the original condition. The basic iron salt above mentioned was easily dissolved again by the addition of a little sulfuric acid. The loss of hydrochloric acid was made good by adding some more sodium chlorid. Only the sodium sulfate produced from sodium chlorid and the sulfates present would have to be removed from time to time, which is easily done by allowing it to crystallize out, it being less soluble than the other salts present. If copper sulfid is much in evidence, its oxidation to sulfate would be favored by making the solution slightly alkaline during the regeneration of the solution for future use.

The process worked also satisfactorily in an acid solutioni. e., on adding sulfuric acid to the above-described mixture the result was the same, only it would be useless addition and make the process a little more expensive, since the reoxidation of the copper sulfid was slower and the loss of hydrochloric acid in the air-current greater; but since the principle is the same the use of an acid mixture is clearly within the scope of my invention. Furthermore, it is evident that one or more of the necessary ingredients may be added to the mixture gradually during the process without changing its essence. For instance, on treating the same Ohio distillate by means of a current of air with ten cubic centimeters each of copper-sulfate and ironsulfate solutions and letting drop in gradually ten cubic centimeters of sodium-chlorid solution the des ulfurization was completed in one-halfhouratordinary temperature. These and many other modifications of the process would be evident enough to any one skilled in the art, and I consider them clearly within the scope of my invention.

The precise quantities of the reagents men tioned above are not essential to the process, and they were, in fact, largely in excess of the theoretical amounts needed; but it is an advantage to employ as large quantities as otherwise permissible, so as to gain in time. The same solution may be used many times.

Temperature has but little influence on the process within the limits prescribed by the nature of the substance acted upon. While the evolution of chlorin and the oxidation are more energetic at a higher temperature, the loss of the more volatile portions of the oil would be too great to allow ofany high temperature being employed. In practice on a large scale the distillates reach the agitator at a temperature of about to Fahrenheit. This temperature is quite favorable for the present process. I have worked it at a temperature as high as to 130 Fahrenheit without producing injurious effects upon the oil and as low as 60 Fahrenheit without making the action too slow. On the other hand, if the temperature of the oil should be too low in wintersay below 50 Fahrenheit-it ought to be warmed up, as otherwise the action would be too slow or would fail altogether.

The presence at one and the same time of the three reagents mentioned above in the mixture was found to be necessary to attain the result sought. It was necessary to have first an oxidizing agent, and, second, hydrochloric acid, (as such or in the form of a salt,) also, third, copper in some form to combine with and eliminate the sulfur. Any single one of these three or any two of them together were ineffective. The further action of the oxidizing agent in oxidizing the copper sulfid was an advantage in practical operation, but was not essential for the removal of sulfur from the hydrocarbons. The copper sulfid might be separated from the mixture and oxidized by itself by any well-known means.

The agitation of the distillate is usually done by a current of air, and this serves here also to supply any oxygen needed during the process for producing the ferric salt and for oxidizing the copper sulfid more or less; but it is clear that the agitation can also be done mechanically and that the oxygen needed can be supplied to the mixed solution previously to its use, so as to form a large quantity of ferric salt which will act as oxidizer.

lrVhile I have described myinveution as applied to Ohio petroleum, it is equally adapted to Texas oil and other products, as I have found by actual practice.

Having now fully described my invention, what I claim isl. The herein-described process of desulfurizing petroleum and its distillates which consists in treating them with an aqueous solution of iron sulfate, sodium chlorid and copper sulfate, as and for the purposes set forth.

2. The herein-described process of desulfurizing petroleum and its distillates which consists in treating them with an aqueous solution of iron sulfate, sodium chlorid and copper sulfate, and agitating by an air-current, as and for the purposes set forth.

3. The herein-described process of desulfurizing petroleum and its distillates which consists in treating them with an acid aqueous solution of iron sulfate, sodium chlorid and copper sulfate, as and for the purposes set forth.

1-. The herein-described process of desulfurizing petroleum and its distillates which consists in treating them with a slightly acid solution of iron sulfate, sodium chlorid and coppersulfate, and agitating by an air-current, as and for the purposes set forth.

5. The herein-described process of desulfurizing petroleum and its distillates which consists in treating them with an aqueous solution of a salt of a metal having two or more easily interconvertible states of oxidation, of a halogen compound, and of a salt of a metal forming a sulfid insoluble in acid solution, as and for the purposes set forth.

'6. Theherein-described process of desulfurizing petroleum and its distillates, which consists in treating them with an aqueous solution of a salt of a metal having two or more easily-interconvertible states of oxidation, of a halogen compound, and of a salt of a metal forming a sulfid insoluble in acid solution, and agitating by an air-current, as and for the purposes set forth.

7. The herein-described process of desulfurizing petroleum and its distillates which consists in treating them with an aqueous solution of an iron salt, of sodium chlorid and of a copper salt, as and for the purposes set forth.

8. The herein-described process of desulfurizing petroleum and its distillates which consists in treating them with an aqueous solution of an iron salt, of sodium chlorid and THEODORE COLIN.

Witnesses: 1

M. LAWSON DYER, JOHN C. KERR. 

